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/*
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 * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
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package java.time;

import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
import static java.time.temporal.ChronoUnit.MONTHS;

import java.time.chrono.Chronology;
import java.time.chrono.IsoChronology;
import java.time.format.DateTimeFormatterBuilder;
import java.time.format.TextStyle;
import java.time.temporal.ChronoField;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalAdjuster;
import java.time.temporal.TemporalField;
import java.time.temporal.TemporalQueries;
import java.time.temporal.TemporalQuery;
import java.time.temporal.UnsupportedTemporalTypeException;
import java.time.temporal.ValueRange;
import java.util.Locale;

/**
 * A month-of-year, such as 'July'.
 * <p>
 * {@code Month} is an enum representing the 12 months of the year -
 * January, February, March, April, May, June, July, August, September, October,
 * November and December.
 * <p>
 * In addition to the textual enum name, each month-of-year has an {@code int} value.
 * The {@code int} value follows normal usage and the ISO-8601 standard,
 * from 1 (January) to 12 (December). It is recommended that applications use the enum
 * rather than the {@code int} value to ensure code clarity.
 * <p>
 * <b>Do not use {@code ordinal()} to obtain the numeric representation of {@code Month}.
 * Use {@code getValue()} instead.</b>
 * <p>
 * This enum represents a common concept that is found in many calendar systems.
 * As such, this enum may be used by any calendar system that has the month-of-year
 * concept defined exactly equivalent to the ISO-8601 calendar system.
 *
 * @implSpec This is an immutable and thread-safe enum.
 * @since 1.8
 */
public enum Month implements TemporalAccessor, TemporalAdjuster {

  /**
   * The singleton instance for the month of January with 31 days.
   * This has the numeric value of {@code 1}.
   */
  JANUARY,
  /**
   * The singleton instance for the month of February with 28 days, or 29 in a leap year.
   * This has the numeric value of {@code 2}.
   */
  FEBRUARY,
  /**
   * The singleton instance for the month of March with 31 days.
   * This has the numeric value of {@code 3}.
   */
  MARCH,
  /**
   * The singleton instance for the month of April with 30 days.
   * This has the numeric value of {@code 4}.
   */
  APRIL,
  /**
   * The singleton instance for the month of May with 31 days.
   * This has the numeric value of {@code 5}.
   */
  MAY,
  /**
   * The singleton instance for the month of June with 30 days.
   * This has the numeric value of {@code 6}.
   */
  JUNE,
  /**
   * The singleton instance for the month of July with 31 days.
   * This has the numeric value of {@code 7}.
   */
  JULY,
  /**
   * The singleton instance for the month of August with 31 days.
   * This has the numeric value of {@code 8}.
   */
  AUGUST,
  /**
   * The singleton instance for the month of September with 30 days.
   * This has the numeric value of {@code 9}.
   */
  SEPTEMBER,
  /**
   * The singleton instance for the month of October with 31 days.
   * This has the numeric value of {@code 10}.
   */
  OCTOBER,
  /**
   * The singleton instance for the month of November with 30 days.
   * This has the numeric value of {@code 11}.
   */
  NOVEMBER,
  /**
   * The singleton instance for the month of December with 31 days.
   * This has the numeric value of {@code 12}.
   */
  DECEMBER;
  /**
   * Private cache of all the constants.
   */
  private static final Month[] ENUMS = Month.values();

  //-----------------------------------------------------------------------

  /**
   * Obtains an instance of {@code Month} from an {@code int} value.
   * <p>
   * {@code Month} is an enum representing the 12 months of the year.
   * This factory allows the enum to be obtained from the {@code int} value.
   * The {@code int} value follows the ISO-8601 standard, from 1 (January) to 12 (December).
   *
   * @param month the month-of-year to represent, from 1 (January) to 12 (December)
   * @return the month-of-year, not null
   * @throws DateTimeException if the month-of-year is invalid
   */
  public static Month of(int month) {
    if (month < 1 || month > 12) {
      throw new DateTimeException("Invalid value for MonthOfYear: " + month);
    }
    return ENUMS[month - 1];
  }

  //-----------------------------------------------------------------------

  /**
   * Obtains an instance of {@code Month} from a temporal object.
   * <p>
   * This obtains a month based on the specified temporal.
   * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
   * which this factory converts to an instance of {@code Month}.
   * <p>
   * The conversion extracts the {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} field.
   * The extraction is only permitted if the temporal object has an ISO
   * chronology, or can be converted to a {@code LocalDate}.
   * <p>
   * This method matches the signature of the functional interface {@link TemporalQuery}
   * allowing it to be used as a query via method reference, {@code Month::from}.
   *
   * @param temporal the temporal object to convert, not null
   * @return the month-of-year, not null
   * @throws DateTimeException if unable to convert to a {@code Month}
   */
  public static Month from(TemporalAccessor temporal) {
    if (temporal instanceof Month) {
      return (Month) temporal;
    }
    try {
      if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) {
        temporal = LocalDate.from(temporal);
      }
      return of(temporal.get(MONTH_OF_YEAR));
    } catch (DateTimeException ex) {
      throw new DateTimeException("Unable to obtain Month from TemporalAccessor: " +
          temporal + " of type " + temporal.getClass().getName(), ex);
    }
  }

  //-----------------------------------------------------------------------

  /**
   * Gets the month-of-year {@code int} value.
   * <p>
   * The values are numbered following the ISO-8601 standard,
   * from 1 (January) to 12 (December).
   *
   * @return the month-of-year, from 1 (January) to 12 (December)
   */
  public int getValue() {
    return ordinal() + 1;
  }

  //-----------------------------------------------------------------------

  /**
   * Gets the textual representation, such as 'Jan' or 'December'.
   * <p>
   * This returns the textual name used to identify the month-of-year,
   * suitable for presentation to the user.
   * The parameters control the style of the returned text and the locale.
   * <p>
   * If no textual mapping is found then the {@link #getValue() numeric value} is returned.
   *
   * @param style the length of the text required, not null
   * @param locale the locale to use, not null
   * @return the text value of the month-of-year, not null
   */
  public String getDisplayName(TextStyle style, Locale locale) {
    return new DateTimeFormatterBuilder().appendText(MONTH_OF_YEAR, style).toFormatter(locale)
        .format(this);
  }

  //-----------------------------------------------------------------------

  /**
   * Checks if the specified field is supported.
   * <p>
   * This checks if this month-of-year can be queried for the specified field.
   * If false, then calling the {@link #range(TemporalField) range} and
   * {@link #get(TemporalField) get} methods will throw an exception.
   * <p>
   * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then
   * this method returns true.
   * All other {@code ChronoField} instances will return false.
   * <p>
   * If the field is not a {@code ChronoField}, then the result of this method
   * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
   * passing {@code this} as the argument.
   * Whether the field is supported is determined by the field.
   *
   * @param field the field to check, null returns false
   * @return true if the field is supported on this month-of-year, false if not
   */
  @Override
  public boolean isSupported(TemporalField field) {
    if (field instanceof ChronoField) {
      return field == MONTH_OF_YEAR;
    }
    return field != null && field.isSupportedBy(this);
  }

  /**
   * Gets the range of valid values for the specified field.
   * <p>
   * The range object expresses the minimum and maximum valid values for a field.
   * This month is used to enhance the accuracy of the returned range.
   * If it is not possible to return the range, because the field is not supported
   * or for some other reason, an exception is thrown.
   * <p>
   * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
   * range of the month-of-year, from 1 to 12, will be returned.
   * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
   * <p>
   * If the field is not a {@code ChronoField}, then the result of this method
   * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
   * passing {@code this} as the argument.
   * Whether the range can be obtained is determined by the field.
   *
   * @param field the field to query the range for, not null
   * @return the range of valid values for the field, not null
   * @throws DateTimeException if the range for the field cannot be obtained
   * @throws UnsupportedTemporalTypeException if the field is not supported
   */
  @Override
  public ValueRange range(TemporalField field) {
    if (field == MONTH_OF_YEAR) {
      return field.range();
    }
    return TemporalAccessor.super.range(field);
  }

  /**
   * Gets the value of the specified field from this month-of-year as an {@code int}.
   * <p>
   * This queries this month for the value of the specified field.
   * The returned value will always be within the valid range of values for the field.
   * If it is not possible to return the value, because the field is not supported
   * or for some other reason, an exception is thrown.
   * <p>
   * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
   * value of the month-of-year, from 1 to 12, will be returned.
   * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
   * <p>
   * If the field is not a {@code ChronoField}, then the result of this method
   * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
   * passing {@code this} as the argument. Whether the value can be obtained,
   * and what the value represents, is determined by the field.
   *
   * @param field the field to get, not null
   * @return the value for the field, within the valid range of values
   * @throws DateTimeException if a value for the field cannot be obtained or the value is outside
   * the range of valid values for the field
   * @throws UnsupportedTemporalTypeException if the field is not supported or the range of values
   * exceeds an {@code int}
   * @throws ArithmeticException if numeric overflow occurs
   */
  @Override
  public int get(TemporalField field) {
    if (field == MONTH_OF_YEAR) {
      return getValue();
    }
    return TemporalAccessor.super.get(field);
  }

  /**
   * Gets the value of the specified field from this month-of-year as a {@code long}.
   * <p>
   * This queries this month for the value of the specified field.
   * If it is not possible to return the value, because the field is not supported
   * or for some other reason, an exception is thrown.
   * <p>
   * If the field is {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
   * value of the month-of-year, from 1 to 12, will be returned.
   * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
   * <p>
   * If the field is not a {@code ChronoField}, then the result of this method
   * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
   * passing {@code this} as the argument. Whether the value can be obtained,
   * and what the value represents, is determined by the field.
   *
   * @param field the field to get, not null
   * @return the value for the field
   * @throws DateTimeException if a value for the field cannot be obtained
   * @throws UnsupportedTemporalTypeException if the field is not supported
   * @throws ArithmeticException if numeric overflow occurs
   */
  @Override
  public long getLong(TemporalField field) {
    if (field == MONTH_OF_YEAR) {
      return getValue();
    } else if (field instanceof ChronoField) {
      throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
    }
    return field.getFrom(this);
  }

  //-----------------------------------------------------------------------

  /**
   * Returns the month-of-year that is the specified number of quarters after this one.
   * <p>
   * The calculation rolls around the end of the year from December to January.
   * The specified period may be negative.
   * <p>
   * This instance is immutable and unaffected by this method call.
   *
   * @param months the months to add, positive or negative
   * @return the resulting month, not null
   */
  public Month plus(long months) {
    int amount = (int) (months % 12);
    return ENUMS[(ordinal() + (amount + 12)) % 12];
  }

  /**
   * Returns the month-of-year that is the specified number of months before this one.
   * <p>
   * The calculation rolls around the start of the year from January to December.
   * The specified period may be negative.
   * <p>
   * This instance is immutable and unaffected by this method call.
   *
   * @param months the months to subtract, positive or negative
   * @return the resulting month, not null
   */
  public Month minus(long months) {
    return plus(-(months % 12));
  }

  //-----------------------------------------------------------------------

  /**
   * Gets the length of this month in days.
   * <p>
   * This takes a flag to determine whether to return the length for a leap year or not.
   * <p>
   * February has 28 days in a standard year and 29 days in a leap year.
   * April, June, September and November have 30 days.
   * All other months have 31 days.
   *
   * @param leapYear true if the length is required for a leap year
   * @return the length of this month in days, from 28 to 31
   */
  public int length(boolean leapYear) {
    switch (this) {
      case FEBRUARY:
        return (leapYear ? 29 : 28);
      case APRIL:
      case JUNE:
      case SEPTEMBER:
      case NOVEMBER:
        return 30;
      default:
        return 31;
    }
  }

  /**
   * Gets the minimum length of this month in days.
   * <p>
   * February has a minimum length of 28 days.
   * April, June, September and November have 30 days.
   * All other months have 31 days.
   *
   * @return the minimum length of this month in days, from 28 to 31
   */
  public int minLength() {
    switch (this) {
      case FEBRUARY:
        return 28;
      case APRIL:
      case JUNE:
      case SEPTEMBER:
      case NOVEMBER:
        return 30;
      default:
        return 31;
    }
  }

  /**
   * Gets the maximum length of this month in days.
   * <p>
   * February has a maximum length of 29 days.
   * April, June, September and November have 30 days.
   * All other months have 31 days.
   *
   * @return the maximum length of this month in days, from 29 to 31
   */
  public int maxLength() {
    switch (this) {
      case FEBRUARY:
        return 29;
      case APRIL:
      case JUNE:
      case SEPTEMBER:
      case NOVEMBER:
        return 30;
      default:
        return 31;
    }
  }

  //-----------------------------------------------------------------------

  /**
   * Gets the day-of-year corresponding to the first day of this month.
   * <p>
   * This returns the day-of-year that this month begins on, using the leap
   * year flag to determine the length of February.
   *
   * @param leapYear true if the length is required for a leap year
   * @return the day of year corresponding to the first day of this month, from 1 to 336
   */
  public int firstDayOfYear(boolean leapYear) {
    int leap = leapYear ? 1 : 0;
    switch (this) {
      case JANUARY:
        return 1;
      case FEBRUARY:
        return 32;
      case MARCH:
        return 60 + leap;
      case APRIL:
        return 91 + leap;
      case MAY:
        return 121 + leap;
      case JUNE:
        return 152 + leap;
      case JULY:
        return 182 + leap;
      case AUGUST:
        return 213 + leap;
      case SEPTEMBER:
        return 244 + leap;
      case OCTOBER:
        return 274 + leap;
      case NOVEMBER:
        return 305 + leap;
      case DECEMBER:
      default:
        return 335 + leap;
    }
  }

  /**
   * Gets the month corresponding to the first month of this quarter.
   * <p>
   * The year can be divided into four quarters.
   * This method returns the first month of the quarter for the base month.
   * January, February and March return January.
   * April, May and June return April.
   * July, August and September return July.
   * October, November and December return October.
   *
   * @return the first month of the quarter corresponding to this month, not null
   */
  public Month firstMonthOfQuarter() {
    return ENUMS[(ordinal() / 3) * 3];
  }

  //-----------------------------------------------------------------------

  /**
   * Queries this month-of-year using the specified query.
   * <p>
   * This queries this month-of-year using the specified query strategy object.
   * The {@code TemporalQuery} object defines the logic to be used to
   * obtain the result. Read the documentation of the query to understand
   * what the result of this method will be.
   * <p>
   * The result of this method is obtained by invoking the
   * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
   * specified query passing {@code this} as the argument.
   *
   * @param <R> the type of the result
   * @param query the query to invoke, not null
   * @return the query result, null may be returned (defined by the query)
   * @throws DateTimeException if unable to query (defined by the query)
   * @throws ArithmeticException if numeric overflow occurs (defined by the query)
   */
  @SuppressWarnings("unchecked")
  @Override
  public <R> R query(TemporalQuery<R> query) {
    if (query == TemporalQueries.chronology()) {
      return (R) IsoChronology.INSTANCE;
    } else if (query == TemporalQueries.precision()) {
      return (R) MONTHS;
    }
    return TemporalAccessor.super.query(query);
  }

  /**
   * Adjusts the specified temporal object to have this month-of-year.
   * <p>
   * This returns a temporal object of the same observable type as the input
   * with the month-of-year changed to be the same as this.
   * <p>
   * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
   * passing {@link ChronoField#MONTH_OF_YEAR} as the field.
   * If the specified temporal object does not use the ISO calendar system then
   * a {@code DateTimeException} is thrown.
   * <p>
   * In most cases, it is clearer to reverse the calling pattern by using
   * {@link Temporal#with(TemporalAdjuster)}:
   * <pre>
   *   // these two lines are equivalent, but the second approach is recommended
   *   temporal = thisMonth.adjustInto(temporal);
   *   temporal = temporal.with(thisMonth);
   * </pre>
   * <p>
   * For example, given a date in May, the following are output:
   * <pre>
   *   dateInMay.with(JANUARY);    // four months earlier
   *   dateInMay.with(APRIL);      // one months earlier
   *   dateInMay.with(MAY);        // same date
   *   dateInMay.with(JUNE);       // one month later
   *   dateInMay.with(DECEMBER);   // seven months later
   * </pre>
   * <p>
   * This instance is immutable and unaffected by this method call.
   *
   * @param temporal the target object to be adjusted, not null
   * @return the adjusted object, not null
   * @throws DateTimeException if unable to make the adjustment
   * @throws ArithmeticException if numeric overflow occurs
   */
  @Override
  public Temporal adjustInto(Temporal temporal) {
    if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) {
      throw new DateTimeException("Adjustment only supported on ISO date-time");
    }
    return temporal.with(MONTH_OF_YEAR, getValue());
  }

}
